Installed it, configured it, pointed it at the public cpython repo, it said 'cloning' and then pegged cpu for about 15 minutes (with about a third to a half of the usage in 'system') and eventually kernel-panicked.
OS 10.13.3 (17D34a) and Docker 17.12.0-ce-mac46 (21698). I don't think it's you, Docker is just still a bit flaky there, which is why I'm asking. I'll try it with something smaller.